They warned that the price of cheese and beef could rise sharply in the event of a no-deal Brexit.

The UK is set to leave the European Union on March 29 2019 and a withdrawal agreement has yet to be reached between the EU and the UK government.

Earlier this week Prime Minister Theresa May said that a Brexit deal was "95% done" but issues remain over the Irish border and backstop issues.

Declan Billington of the Northern Ireland Food & Drink Association said that the "viability of the dairy section is being brought into question" because 30% of milk from Northern Ireland is processed in the Republic of Ireland.

He said that Northern Ireland lacked the infrastructure to process the milk.

"Over the distance the UK is a great opportunity for us to expand into but we don't have five months to build the factories to make the butter and cheese," Mr Billington said.

"There is a real fear that unless the government intervene in a hard Brexit to support the industries while they transition there could be serious casualties."

Asked about those who say a no-deal would not pose a problem Mr Billington said that giving five months to get ready for Brexit would be "devastating" for local industry.

He said that Northern Ireland businesses were facing a "cliff edge" due to the lack of preparation and clear guidelines ahead of Brexit.

Director of the Northern Ireland Retail Consortium Aodhan Connolly said that a no-deal Brexit was "not an option" for Northern Ireland businesses.

Mr Connolly said that if Northern Ireland received "favoured nations status" with the World Trade Organisation then consumers would see the cost of beef rise by 37% and cheese by 43%.

"We're already at the lowest baseline economically of any of the regions and countries throughout the UK, quite simply the Northern Ireland consumer does not have the ability to absorb these cost rises that could come from a no-deal scenario," he said.

"Why are people in Northern Ireland going to have to pay more for their cheese when they can get it either from the surplus milk that there's going to be or from buying good old English cheddar," he said.

Mr Billington said that the Northern Ireland dairy industry relied on factories in the Republic of Ireland.

"The UK is running a 30% deficit on cheese, alot of that is made up from countries like Ireland, the milk from Northern Ireland goes to the South to be made into cheese. Years ago we are argued that we needed a level playing field to be able to build the factories in Northern Ireland to service the UK market," he said.

"The food deficit is twice the size of our output so over the distance there was always a big opportunity. The all-island market evolved and the factories are on the other side of the border and the milk will not be able to move south to service those factories. We do not have the factories in the North to make butter or cheese."

Sir Christopher said that the cheese market would produce a "great post-Brexit opportunity" for Northern Ireland.

"If you gave us a five-year transition period before we hit the brick wall we would break your arm to take the opportunities for Northern Ireland in the UK market. We're not being given five years, we're being given five months," Mr Billington said.

Sir Christopher said businesses had been aware that the UK was leaving the EU for more than two years and questioned the lack of preparation.

"Nobody has ever given any guarantee that there would be a deal, why is it that none of you seem to have been making any contingency plans?," he asked.

"You've known we've been coming out of the EU since June 2016 and now you're just waking up with five minutes to go that there might not be a deal. You've not done a pretty good job have you?," he said.